The characterisation of fractures in reservoir formations can be important for understanding and predicting the behaviour of reservoirs. For example, fractures intersecting drilled wells may assist the flow of hydrocarbons from the reservoir and so increase production. Conversely, fractures may allow water to flow into wells and so decrease production.
Fractures at distances from drilled wells can also influence flow patterns at the wells. Furthermore, at distances from wells, generally only indirect seismic measurements of fractures are available, and so any information that can be extracted from seismic data can be of great value.
WO 2008/086352 describes a methodology for mapping fracture networks from seismic data using fracture enhancement attributes and fracture extraction methods.
For example, borehole data can be used to determine modes of fracture, and in particular whether fracture clusters or networks would be detectable in surface seismic data. It can also provide information on fracture network inclination (i.e. average inclination of the fractures in a network relative to the horizontal) and strike azimuth (i.e. average direction of intersection of the fractures in a network relative to the horizontal).
Discontinuity extraction software (DES), for example as described in U.S. Pat. No. 7,203,342, may then be utilised to extract 3D volumes of fracture networks from surface seismic data.
Extracted fracture networks may further be parameterised in terms of the strength of their seismic response, and on their length, height and width.
Lacking from such known methodologies for mapping fracture networks, however, is characterisation of the dynamic behaviour of fracture networks.